We went through this with music, and DRM-free files won. They were rightly seen as intrinsically more valuable, and no one was willing to buy a restricted file

We went through this with music, and DRM-free files won. They were rightly seen as intrinsically more valuable, and no one was willing to buy a restricted file when a regular mp3 of the same content was available for the same price. The same is true of ebooks. Many publishers offer DRM-free ebooks, but they cannot compete with kindle ebooks on price. A freely distributable PDF is worth more to me than a one with DRM, but not infinitely more. Eventually the prices will equalize and everyone will buy open formats.